Backups for Exchange 2003 are failing

The backups for my exchange 2003 server are failing, however users are able to send and receive mail and all the services are started and not giving any problems.

Also the following error (see below) keeps popping up.
I ran the ISINTEG Util, as well as did a chkdsk and everything ran through ok .

Any ideas on what can fix this?

Event Type:      Error
Event Source:      ESE
Event Category:      Logging/Recovery
Event ID:      478
Date:            10/18/2008
Time:            11:34:38 AM
User:            N/A
Computer:      servername
Description:
Information Store (3228) The streaming page read from the file "D:\Program Files\Exchsrvr\mdbdata\priv1.stm" at offset 694689792 (0x0000000029682000) for 4096 (0x00001000) bytes failed verification due to a page checksum mismatch.  The expected checksum was 3484008644 (0x00000000cfa9c0c4) and the actual checksum was 2309737967 (0x0000000089abcdef).  The read operation will fail with error -613 (0xfffffd9b).  If this condition persists then please restore the database from a previous backup.